This invention relates to a digital clock, more particularly to a digital clock provided with a time switch mechanism.
Various types of the digital clocks of the type just mentioned have been proposed in the past, but a digital clock of the most common type comprises a hour display unit, minute display unit, a second (the least significant digit) display unit which also serves as an operation display unit which displays whether the clock is operating continuously or not and a timer setting wheel utilized to set time.
The layout of various component elements of such digital clock has been limited by the following reasons.
More particularly, while a synchronous motor is used to drive a hour display unit of the drum type, leaf type or shutter type, it is necessary to locate the synchronous motor on the lower digit side of the hour display unit for the purpose of simplifying the motion transmission mechanism.
Furthermore, in order to improve the convenience of use and appearance it is desirable to locate the hour display unit at the center and to locate such auxiliary mechanisms as the second display unit or the operation display unit and the timer setting wheel display unit on both sides of the hour display unit.
Since a buzzer incorporated with a time switch mechanism is operated by the leakage flux of the synchronous motor, it is desirable to locate the buzzer as close as possible to the synchronous motor in order to simplify the motion transmission mechanism thereby decreasing the cost.
Moreover, it is desirable that the assembly and disassembly of the clock can be made as readily as possible. Especially, since the time switch mechanism is fabricated with a relatively large number of small component parts and moreover since the parts are constructed to rotate or swing it has been desirable to simplify troublesome assembling operation.
Where a so-called repeat mechanism is provided which repeatedly rings at a definite interval when the time switch operates it is desirable to simplify as far as possible such repeat mechanism for the purpose of avoiding misoperation. Of course, such mechanism should have a simple construction and can be assembled readily.
In consideration of these points, it was a common practice in the past to adopt a structure such as in U.S. Pat. No. 3,495,396.
In all such structures, however, an exclusive lever independent of the rest of the transmission systems was used for the transmission system between the timer layer related to the timer setting wheel and the buzzer system disposed on the side of the synchronized motor.
Further, the prior art time switch system mentioned above was in a structure for which the component parts had to be assembled in order from one direction, and for this reason, when a part of the structure required adjustment after the completion of assembling, the whole structure had to be dismantled.